1. Field of the Invention
The present invention relates to an error correction encoding method for a high-density storage media.
2. Description of the Related Art
Data on a digital versatile disk (DVD) are generally encoded in a predefined error correction code (ECC). The ECC code is the two-dimensional Reed-Solomon code (hereinafter, referred to RS code) using an outer parity (PO) encoder and an inner parity (PI) encoder. Data bytes to be written in a disk are arrayed in rows and columns to be PO- and PI-encoded.
FIG. 1 shows the format of an ECC block in accordance with the DVD standard format. Data unit input to the RS encoder is (172×192)-symbols (a symbol size may be one byte) in size and has a block structure of a 172 columns by 192 rows matrix form. For every column of the input data block, the PO encoder appends outer parity of sixteen bytes to a 192-byte column in the column direction. The outer-error-correction encoded columns, each being 208-byte long, are then stored in a buffer of the RS encoder.
After outer-error-correction encoding of 172 columns is completed, 172 columns become arranged sequentially in the buffer. Then, for every row of the data block in the buffer, inner-error-correction encoding is performed sequentially by the PI encoder by appending inner parity of ten symbols to a 172-symbol row in the row direction.
In this way, the RS encoder produces the ECC block shown in FIG. 1. As a result, the ECC block is 37,586 bytes in size (182×208=37,586). Each symbol of the ECC block is then modulated by ESM (Eight to Sixteen Modulation) method, which converts 8 bits (one byte) to 16 channel bits so as to be written onto a storage medium like DVD.
The error correction encoding method using ECC block structure shown in FIG. 1 has been devised based on data density of current optical disks like DVD. It is, however, expected that for next-generation storage media of higher data density than DVD the error correction encoding method of the conventional art is vulnerable to burst errors.
It will be likely that next-generation high-density storage medium, the density of which is twice as high as DVD, has two times more channel bit errors than DVD for a scratch of the same size. Therefore, the development of an effective error correction encoding method is required to enhance the capability of correction of burst errors on next-generation high-density storage media.